1. Field of the Invention
The invention relates generally to all types of body fluid test devices and methods, and specifically to oral drug use tests.
2. Description of Prior Art and Related Information
Some of the most common body fluids tests comprise immunoassay tests. Immunoassay tests are generally based on the competition between a target antigen and a known amount of antigen derivative. The antigen derivative is generally the antigen or an appropriate analog thereof. A predetermined amount of a specific antibody provides a limited number of binding sites for which the antigen and antigen derivative compete. These types of immunoassays have been used extensively in urinalysis devices and methods.
Some immunoassay devices are lateral flow devices, and the antibodies are movably supported on a solid support such as a porous pad. The antigen derivatives are deposited as immobilized indicator lines downstream of the antibodies, whereby the target antigens in a fluid sample flow laterally as a liquid matrix by capillary action through the solid support. In this case, the antibodies are normally colored for visual indication. The fluid sample carries the antibodies downstream towards the indicator lines of immobilized antigen derivatives while a reaction takes place between the target antigens and the antibodies. Any antibodies that have not reacted with the antigen in the sample bind to the antigen derivatives at the indicator lines. When little or no target antigen is present in the sample, most or all of the colored antibodies are carried downstream to the indicator lines of the immobilized antigen derivatives. At the immobilized antigen derivatives, the colored antibodies bind together with the antigen derivatives in such concentrations that the colorant of the antibodies becomes readily visible. It is also known that the antigen derivatives and the antibodies can be interchanged. That is, the antigen derivatives can be labeled with colorant and movably placed in the solid support while the antibodies are placed as immobilized deposited indicator lines downstream.
A majority of the immunoassay test devices and methods of the past are for urinalysis. While urinalysis testing has many advantages and is a well accepted type of testing, urinalysis does have certain drawbacks.
Urinalysis devices have perhaps been popular because of the relative ease of obtaining the sample as compared to taking blood. Historically, urine samples could be taken with little or no contamination to the samples. However, in the case of abused drug tests, there are added concerns of intentional adulteration of the sample by the donor.
Urinalysis has always had the drawback of requiring the handling of urine, which many operators find objectionable. Another drawback to utilizing urine samples is that the kidneys function as a filter for blood. Hence, the urine samples vary with physiological and pathological status, and do not closely resemble the dynamic chemical concentrations in the blood.
Typically, urinalysis utilizes large sample sizes. As such, urinalysis often has the disadvantage that the sample containers take up much space. The larger sample sizes typically provided by urinalysis sampling are advantageous for some tests. For example, abused drug testing requires a confirmation test in addition to a prescreening test. Therefore, the overall sample typically must be larger. In some instances however, the collected sample is insufficient for both an initial prescreening test and the confirmation test. In such cases, a second sample is needed. However, the results from the second sample may not be properly comparable to the prescreening test results from the original sample because the second sample most likely does not have the same constitution as the original sample, which could lead to legal challenge by the donor. Therefore, sampling for both the prescreen and confirmation testing must be repeated on a common sample.
A drawback to the conventional lateral flow immunoassay urinalysis devices is that they require a measure of privacy during sample collection. As such, the extent of contamination to the sample cannot be adequately monitored during sample collection. In order to overcome this deficiency, some government agencies have established the policy of having an attendant of the same sex observe during sample collection in order to identify accidental or intentional contamination of the sample. These provisions, of course, are embarrassing for the donor and the observer and add to the cost of testing.
In light of the many drawbacks of urinalysis, it is clear that viable alternatives for testing other body fluids may be of great interest. For example, immunoassays on oral fluids are particularly advantageous in overcoming the need for privacy during sampling in urinalysis testing.
A few devices have been developed for lateral flow testing of oral fluids. Even though the devices developed for oral fluid testing have overcome some drawbacks of conventional urinalysis and including some drawbacks associated with lateral flow urinalysis, the oral immunoassay test devices still have deficiencies of their own. For example, the lateral flow immunoassay test devices for oral fluid have means for both collection and prescreen testing of oral fluid. However, they are deficient in providing structure for preserving a portion of the sample for confirmation testing in a single device. Furthermore, these devices are deficient in teaching a method of preserving a portion of the sample for confirmation testing.
Alternatively stated, the devices of the past require a cumbersome amount of separate equipment and steps to accomplish collecting, prescreening, and confirmation testing of samples. This is due to the fact that confirmation testing is not provided for by the oral fluid test devices and due to the other drawbacks set forth above for urinalysis devices and methods.
A drawback of immunoassay testing of oral fluids is that they generally have lower concentrations of antigens to be detected. Furthermore, the viscous nature of oral fluid impedes flow of the oral fluid to or around any reagent. Another drawback of the oral test devices and methods of the past is that the sample size is small and only serves for a prescreen test. Yet government regulations require confirmation testing before relying on a positive result of a prescreen test. Thus, if a confirmation test is desired, then a second sample has to be taken.
Taking two separate samples for prescreening and confirmation is problematic since it is not clear whether both samples will contain the same substances, as discussed with regard to taking a second urinalysis sample above. A difference in the contents of a second sample from a first sample is more probable if any time lapses between sampling, for example when a prescreen test is positive and the subject person has to be called back for a second sample. Furthermore, getting a second sample requires added time and inconvenience. The limited use of immunoassays of oral fluids is evidence that oral test devices and methods of the past have not found ways to take advantage of the inherent positive aspects associated with oral tests. Apparently, the devices of the past have not provided adequate solutions to the problems discussed above.
The devices of the past also fall short in providing reagents for both adulterant chemicals added to the body fluid at the time of testing and antigens that were present in the body fluid prior to a time of testing. Additionally, the devices of the past are deficient in providing a large number of reagents in order to detect multiple antigens in the sample with a single test.
Due to the many deficiencies and drawbacks of the test devices of the past, it is apparent that there is in need in the art for a simple device that incorporates as much of the required testing as possible in the single device, and that reduces the number of steps required. In addition, there are additional needs for a viable oral testing device and solutions to the other deficiencies set forth above.